Air Fryers and Cancer

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Air fryers are a relatively new appliance designed to be an alternative to conventional deep frying. There are a few ways in which air frying could affect the nutritional content of food and cancer risk. Air fryers use less oil—which avoids the need for reheating oil—and may affect the amount of acrylamide—chemicals that are classified as group 2A carcinogens—that are produced.

But despite potential advantages, it's important to keep in mind that the type of food you eat may, in many ways, be more important than the way in which it's prepared.

air fryer with french fries

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Basics

Air fryers became available in 2010 as an alternative to deep frying. Since many people enjoy fried foods, the ability to prepare foods that were crunchy despite using less oil led to their rapid rise in popularity even though longer cooking times are often required.

How They Work

When looking at potential advantages or disadvantages of a cooking method, it's helpful to understand exactly how the food is heated. Air fryers differ from deep fryers in that they are essentially a countertop convection oven. To heat food, the appliance uses a fan to circulate tiny oil droplets and hot air around the food. The crispiness that's attained is due to fluid being removed from the food in the process.

Air Fryers vs. Deep Frying

Air frying and deep frying differ in the amount of oil used, and the use of oil (especially reheated oil) raises some concerns with regard to health. Longer cooking times, however, may lead to greater formation of carcinogens as well. We will take a look at different factors to consider when weighing air frying as a cooking method.

Oils, Calories, and Obesity

While some oils are thought to be healthier than others, too much of any type of oil can be unhealthy.

Oils and fats have calories. The intake of more calories, in turn, can lead to obesity. As the rate of obesity increases in the United States, its link to cancer is of rising concern. Rising obesity rates are felt to be behind the increasing incidence of some cancers in young people.

At the current time, being overweight or obese is considered a risk factor for 13 different types of cancer. These include: 

  • Meningioma
  • Multiple myeloma
  • Postmenopausal breast cancer
  • Esophagal
  • Thyroid
  • Pancreas
  • Uterus
  • Kidneys
  • Ovaries
  • Colon
  • Rectum

In general, much less oil is needed when cooking with an air fryer than a deep fryer. Sometimes only a small amount of cooking spray is needed, and when added to breading, a teaspoon may be sufficient.

In one study, cooking French fries cooked with an air fryer had 75% less fat than those cooked by deep-frying.

Carcinogens

One concern about any cooking method is the formation of carcinogens (cancer-causing substances) in the cooking process, such as acrylamide and those that are produced when repeatedly heating oils.

Reheated Oil

When cooking oil is reheated (referred to as "thermally abused oil" or "repeatedly heated cooking oil" in studies), it results in breakdown products (hydrolyzed, oxidized, polymerized byproducts etc.) as well as polycyclic aromatic hydrocarbons (PAHs) that may cause oxidative stress. Oxidative stress, in turn, may lead to damage in the DNA of cells that could potentially contribute to the development of cancer (oncogenesis).

In fast food establishments as well as in the home, oil in a deep fryer is often reused to reduce cost. In some countries (such as France, Austria, Japan, Finland, and others), the quantity of breakdown products in oil (and hence, the number of times oil may be reheated) is regulated. There are currently no regulations in the United States.

Studies looking at potential mechanisms (how these compounds might cause cancer) and epidemiological studies looking at the incidence of cancer raise concern over reheated oils.

Inhalation and ingestion of reused oils have also been found to result in a number of changes in cells (such as chromosomal damage) that are linked to cancer. A review of studies has also linked reheated cooking oil to cancers of the breast, lung, colon, and prostate.

In addition to being a possible risk factor for cancer, reheated oil may also be of concern for those who have already been diagnosed with cancer.

In people who have breast cancer, metastatic disease (stage 4 cancer) is responsible for the majority of deaths. Most people with stage 4 breast cancer are initially diagnosed with early-stage breast cancers that later recur, and it's thought that roughly one-third of early-stage cancers will recur at a distant site at some time.

Researchers looked at the potential for repeatedly reheated oil to promote the growth and spread (metastasis) of breast cancer in mice. It was found that mice who were fed reheated oil were much more likely to have their breast tumors spread to their lungs. While there are many differences between mice and humans and we don't know what effect reused oil may have in women with early-stage breast cancers, some physicians recommend that women with breast cancer minimize their exposure to reheated cooking oils until we know more.

In a different study, researchers looked at the effect of reheated oil on colon inflammation and tumor formation in mice. Mice who were fed reheated oil had both increased inflammation and increased tumor formation in their colons. As with the breast cancer study, findings in mice don't necessarily translate to humans, but a degree of caution may be in order.

Fortunately, as noted earlier, air fryers not only allow for the use of much less oil but omit the need to reheat previously used oil.

The Risks of Reheated Oil

Repeatedly heated oil (either eaten or inhaled) has been linked to cancer in population studies, and, at least in mice, has been associated with recurrence and metastasis (spread) of breast and colon cancers. Fortunately, air frying foods eliminates the need to reuse oils.

Acrylamides

Acrylamide are chemicals that are formed in a reaction between the amino acid asparagine and sugars when cooking starches (such as French fries) at high temperatures.

At the current time, acrylamide is considered a group 2A carcinogen for humans, though recent studies have cast less concern on these substances. Most studies have failed to demonstrate an association between acrylamide and cancers with the exception of some possible increased risk for cancers including: 

  • Kidney
  • Uterine
  • Ovarian cancers

Since air fryers require longer cooking times than deep fryers, there was some concern that acrylamide content of the foods would be higher in air fryer cooked products. A 2020 study looking at air frying (breaded chicken meat), however, found that air frying could reduce the amount of acrylamide formed when compared with deep frying. Air frying also resulted in less formation of polycyclic aromatic hydrocarbons.

For those who remain concerned, a different study found that preheating French fries with a solution of citric acid, glycine, calcium lactate, sodium chloride (table salt), and vitamin B2 (nicotinic acid), compounds that are present in many prepared frozen French fries products, reduced the formation of acrylamide by 90%.

Other Health Concerns

Researchers have raised a few other health concerns that may or may not affect the role of air fryers when it comes to cancer risk.

Potential for Food Poisoning

Food poisoning is very common in the United States, and with any cooking method, it's important to look at the relative risk. In the United States, around 48 million people are affected by food poisoning each year, resulting in 128,000 hospitalizations and 3,000 deaths.

A 2019 study compared the risk of food poisoning (using a cocktail of salmonella in frozen breaded chicken strips) that was cooked in an air fryer, a deep fryer, a toaster oven, and a conventional oven. While deep frying was most effective in eliminating the bacteria, both the air fryer and toaster oven performed poorly. What this means on a practical level is that cooking instructions provided on packaging for deep fryers may not be adequate for foods prepared by air frying.

Cholesterol Oxidation Products

The high temperatures used to cook fish in an air fryer are associated with the formation of cholesterol oxidation products (COPs). COPs, in turn, have been linked to heart disease and some other chronic diseases.

While this is of some concern, it was found that adding mixture of spices to the fish before it was cooked (a combination of parsley and chives was the best) significantly reduced the production of COPs during air frying.

Aesthetics

Some people prefer the result of air frying, as foods may be crunchy all around (in contrast, for example, to pan frying). Some may also prefer that the food tastes less greasy.

Safety

Air fryers have a clear advantage when it comes to safety issue. Hot oil in deep fryers or even in pan frying has less to many burns. While safety precautions are certainly still needed with air frying, the reduced need for oil is clearly an advantage in this way.

A Word From Verywell

When looking at the use of an air fryer or deep fryer for cooking, it appears that an air fryer may have some advantages when preparing fried food in a cancer prevention diet. That said, there is a big caveat. Many of the foods that are prepared in an air fryer (for example, French fries and other processed foods) are not the healthiest choices for lowering the risk of cancer or other chronic diseases.

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